My 2006 HHR had a coolant leak that I fixed. I ended up replacing the thermostat, coolant temp sensor, upper and lower radiator hoses, the plastic T in the upper hose and the radiator cap. All with GM parts. When I got it put back together and got it running it set the P0107 code, while I was looking into that it also set a low voltage code. I could actually watch the battery losing voltage on the scan tool, so I replaced the battery. I have since replaced the MAP sensor with a new GM one, cleared the code went for a long drive and it ran great! Parked it and assumed it was fixed. My kid took off in it and the check engine light came on again with the same P0107 code. What am I overlooking?

 

Here's some help https://www.obd-codes.com/p0107

 

Before you run out and get a new ECM note that is LAST on the list and highly unlikely.
Since it seems to be draining your battery I would be looking for compromised wires shorting somewhere.
The test procedure in the previous link is sound.
Also, check fuse #23 underhood fuse box.

 

Thanks for the help. One thing I forgot to mention is I tried to start the car with the air filter assembly off which meant the mass airflow sensor was disconnected and this is when the code problem started. Is there a possible connection?

 

Yes, if you damaged the wiring when taking it apart or putting it back together. Have you tried re-seating the MAF connector?

 

That would give different codes.